The Little Mermaid's Brother
by superkoola
Summary: One-shot: This is the story of how Ariel, the Little Mermaid, came to found her adopted brother, Tethys, when she was eight years old, and Tethys was just a baby.


In the outskirts of the underwater city of Atlantica, two figures are swimming amongst the beautiful coral reefs. One of them is a fifteen year old mermaid with long, beautiful red hair and a green tail. The other is a smaller mermaid; a little boy around the age of 7, with short black hair, green tail like hers, and has a slightly dark skin in comparison to her fair skin as well.

The 15 year old mermaid is named Ariel, and the little merboy is named Tethys, her adopted brother. Why these two are taking a swim at such a fine day? Well, let's take a look. Shall we?

* * *

Ariel was quickly swimming above the coral, her tail causing some underwater sand to be pushed upwards from the force, before settling back down. She briefly turned back to her little brother. "Come on, Tethys! We're almost there!" she called out cheerfully. Tethys sighed as he struggles to keep up.

"Hold on, Ariel! I can't swim as far, or as fast as you!" he called out. Ariel giggled. "Well, this should be a good exercise!" she said before she continued, swimming much faster than before. Tethys groaned.

"Come on! Why do you and your other sisters hate me so much?! What did I ever do to you?!" he whined. Ariel just had to laugh some more. "You were being you; adorable! A bit lazy at times, but still adorable! As well as intelligent!" she called out.

Tethys giggled at her compliment, and that pushed him to go even further. Ariel saw the determination in his face, and she turned ahead to see where she was going.

Eventually, Ariel arrived at a spot near the edge of the coral reef. "Here we are!" she said. Tethys was heard panting, yet he just continues to swim towards. "I'm coming! I'm coming for you, you sneaky little cheater!" he cried, arms reaching out.

Ariel however, just smirked, pushing herself out of the way and snagged Tethys. "Too slow!" she said as she spun around, making Tethys laugh and wiggle his tiny tail, before Ariel finally lets him go. Tethys grabbed and shook his head a bit, feeling dizzy, before turning towards her, still giggling.

"Hahahaha…I hate you, Ariel." Tethys said once he finally regained composure, though he still kept a smile on his face. Ariel giggled. "I love you too, Tethys." She said as she ruffled his hair. Then the two of them looked at where Ariel was looking at.

"Here we are. This is where I found you." She said as she swam ahead. Tethys looked on, and grew confused. There, was a small underwater cave. Tethys tilted his head in confusion, before following Ariel towards the cave.

" _This,_ is where you found me?" he asked as they entered the mini-cave. Ariel nodded. "Yep. It really looked like a small mini-home most homeless merpeople live in." she replied as they began to look around. Inside was mostly desolate for the most part, save for an empty crib, beginning to grow tiny coral from not being used for so long. There are also shapes that showed that there were picture frames that used to be hung there years ago.

"Wow." He said, looking at the bed. "Right here?" he asked. Ariel nodded. "Yep. And good thing too, because…well, you were in danger." She said, as she approached him. Tethys looked at her with confusion and shock.

"What do you mean?" he asked. Ariel sighed and shook her head. "Well, you were a baby at the time, so I doubt you remember what happened." She murmured to herself, before she looked at him.

"Why don't you have a seat here? This might take a while to explain." She started as she gestured Tethys to a nearby sea rock. Tethys looked at her in concern. "Is it that bad?" he asked. Ariel nodded.

"Yes…I had nightmares of that night for weeks because of that encounter." She explained. She then sighed as she then placed her arm around his shoulder.

* * *

 _*Flashback*_

" _ **It happened just seven years ago when my best friend, Flounder and I were playing Kelp Tag in this same reef."**_ _Present Ariel explained as we see a young, 8 year old Ariel chasing a yellow fish with blue stripes named Flounder with a strand of kelp in her left hand. Both of them were having a fun time together, chasing one another amongst the colorful field of coral._

" _I'm gonna catch you, Flounder!" young Ariel called out with a cheery tone. Flounder just laughed as she was about to come in closer. So, not wanting to take a turn and risk losing, he performed "evasive maneuvers." In that he, rather clumsily, tries to zig-zag around the reef to avoid the kelp. Short and sweet to the point, it doesn't work, and Ariel almost caught up with him._

" _ **I was almost catching up with him, when suddenly…he stopped right in front of me."**_ _Present Ariel said as Flounder suddenly came to a complete stop, making young Ariel bump into him, sending Flounder flying forwards, before crashing into a small tunnel. Young Ariel shook her head momentarily to clear and steady her mind from the collision, before she noticed Flounder struggling to get out. "*gasp!* I'm coming, Flounder." She said as she swam towards him, and with a bit of a struggle, she was able to get him out with a_ _ **POP!**_

 _Flounder shook his head, before turning to Young Ariel. "Why did you stop? Is something wrong?" she asked in concern. Flounder looked at her guiltily for moment, before he turned towards his right, pointing at it. "I thought I heard something. Come on." He said before swimming towards the direction._

" _ **I was confused, as I didn't hear anything at first."**_ _Present Ariel began as Young Ariel looked at Flounder, eyebrow raised in confusion._ _ **"But since I was…well, not playing anymore, I began to listen more clearly,"**_ _Present Ariel added on as Young Ariel followed Flounder, now beginning to listen to the noise._

 _As she draws closer, the noise began to grow more audible. It sounded like…crying. A merbaby's crying!_ _ **"And once I was able to figure out what it was…Oh, I couldn't get there fast enough."**_ _Present Ariel finished as Young Ariel began to swim faster, heart pumping in anticipation._

 _Soon, Young Ariel and Flounder arrived at an underwater cave entrance. The noise was getting louder._

" _It's coming from there." Flounder said as Young Ariel tilted her head in confusion. Then she swam towards the cave entrance, frightening Flounder. "Where are you going, Ariel?" he asked. Young Ariel turned to look at him._

" _I've got to take a look at what's inside. It sounds like a merbaby." She said. Flounder raised his brows in fright. "W-What if it's not a merbaby?! W-What if it's one of those…I don't know what creatures are; b-but what if it's them trying to lure you in by copying the sounds of a merbaby crying?" Flounder asked._

 _Young Ariel looked at him in confusion. "Flounder…you really need to head outside more often." She said. She then shook her head. "Don't worry, I'll be back!" she added before swimming right in, leaving a worried Flounder to wait near the entrance, in case any sharks try to snag on him from nearby._

 _He wasn't paying attention to a silhouette of a torpedo-shaped predator nearby…_

 _Meanwhile, Young Ariel swam inside the small space in the cave. It was a mess; marks on the walls, a torn portrait frame on the wall, and a small crib nearby. There was a tiny merbaby lying inside the crib. Young Ariel gasped silently._

" _ **And there you were. Lying inside the crib."**_ _Present Ariel stated as Young Ariel swam over the crib, taking a look at the merbaby inside. It was fair skinned like hers if only slightly darker, a green tail like hers, and black hair that was beginning to grow from his head._

 _Young Ariel gasped slightly, making the baby stop crying. The two of them locked eye contact with each other for a while. The baby then smiled as he then flapped his tiny tail, apparently trying to swim properly while reaching his arms out to try and grab her. Young Ariel smiled at she reached down, and picked him up._

" _Hey there, little guy." She cooed softly as she tickled his nose with hers, making the baby giggle._

" _ **Seeing you for the first time…it touched me in ways I CANNOT begin to describe in words. Sadly, at the time, I thought your parents were still around, so..."**_ _Present Ariel explained as the two looked at each other, smiling and giggling. "Hmm…now where are your parents, little guy?" she asked as she then began to look around, swimming towards the exit._

 _Flounder then saw Young Ariel swimming out, holding the baby in her arms. He sighed in relief. "Phew…I thought that was…I still don't know the creature's name." he said. Young Ariel shook her head as she swam closer to it._

" _We should find his parents. They can't be far." She instructed as she swam ahead, the baby giggling in the process. Flounder looked at her in confusion, then he looked back at the cave, before swimming after her._

" _Um…that place is destroyed. I…I don't think the baby's parents are around here." He said. Young Ariel looked at her friend, looking a bit shocked and concerned. "Flounder, what are you saying? We'll find them. Won't we?" she asked._

 _Flounder nodded rapidly. "N-No. I-I mean of course. Of course we'll find them, i-it's just," he stuttered. But as he continued rambling, no one was paying attention to a large, blackened silhouette slowly approaching them from behind._

" _ **We were busy trying to discuss how we will find your parents, because at the time, we thought they just left."**_ _Present Ariel explained._ _ **"T-Then what?"**_ _asked Present Tethys. Present Ariel sighed._ _ **"Well…**_ **he** _ **showed up."**_ _She said._

 _Young Ariel and Flounder felt a presence behind them, and they slowly turned around. Suddenly, their eyes widened, and they screamed in horror as a large, heavily scarred Great White Shark with an empty socket where it's right eye should be chomped its jaws, missing them by a mere inch._

 _Young Ariel grabbed Flounder as they swam for their lives, the shark chasing after them._ _ **"One-Eye. That horribly disfigured, cruel eating machine just popped out, and gave us a wild chase."**_ _Present Ariel explained as Young Ariel and Flounder were being chased, swimming underneath corals in an attempt to dodge One-Eye's bites, which they did, only by a few inches._

 _Young Ariel then pushed Flounder into a small hole, and she swam after them, just as One-Eye slammed his head against the tiny hole. The three friends pushed themselves back, the baby crying out loud as One-Eye continued trying to bite through the hole, primitive animal instincts preventing the shark from thinking rationally._

" _ **From there…I thought we were gonna die. The hole wouldn't hold forever,"**_ _Present Ariel explained as the hole was beginning to crack. Young Ariel then noticed something in One-Eye's mouth; it appeared to be…something horrific._

" _ **And the worst part, looking back now…was what was inside One-Eye's mouth."**_ _Present Ariel explained._ _ **"Wait…don't tell me…"**_ _Present Tethys said. Young Ariel recoiled in horror once she saw the remains of an arm, now reduced to a skeleton, just before One-Eye closed its mouth on the top of the hole._

" _ **The thing is…Flounder and I wouldn't be alive…we never would've had a new friend to take care of, had it not been for daddy."**_ _Present Ariel said as there was a humming sound in the background. One-Eye was then pushed back by a bright ray of light._

" _GET AWAY FROM THEM!" A familiar voice shouted. One-Eye turned to the direction of the voice, before it swam away, not wanting to cause itself anymore injuries. Young Ariel and Flounder stayed there for a while, too scared to move, while the baby whimpered, having stopped crying when One-Eye was driven away._

" _Ariel? Flounder? Are you two alright?" a voice asked as their savior; a large merman with a long, brown beard and wielding a trident, soon moved into view._

 _This was Ariel's father and ruler of the seas; King Triton._

 _Young Ariel soon sighed in relief as she swam out, hugging her dad. King Triton hugged her back in relief, happy that her daughter is alright. Flounder swam beside her and bowed down in happiness._

 _Then, King Triton heard a mumbling sound. He and Young Ariel pulled back, and his eyes widened upon seeing the baby in her arms._

" _ **After daddy saved us…well, that's how he first met you, Tethys."**_ _Present Ariel said as Young Ariel gave a shy smile._

 _*Flashback ended*_

* * *

"Daddy was a bit unsure of what to do with you at first. He was a little bit worried how his family's image would look with someone who's…well, not of royal blood like mine." Ariel explained as she took Tethys's hand, and swam along the seafloor. Tethys looked at her in confusion.

"What do you mean?" he asked. Ariel sighed to herself in sadness. "Well…when dad decided to adopt you – which took some convincing from me and some of my sisters – it caused a split in our family." She said.

"A split?" he asked. Ariel nodded. "Attina, Adella, Arista and I are happy to have you with us." She said with a smile as she pulled him closer to her. "However, Alana, Aquata and Andrina are…well, they are still getting used to having you around." She explained.

Tethys then looked at the ground, nodding in understanding. He could very well remember the strange looks the latter three mermaids give him sometimes…especially Aquata. "B-But it's not my fault." Tethys said, hand drawing across the sand, making some of it float up for a moment.

Ariel looked at him and shook her head. "Of course not. It's just…that's how tradition usually works. Personally, I find that as stupid as the ban of music." She said. Tethys looked at her. "Really? You love me that much? Even though I'm not only _not_ royalty, but also…the only son of the family?" he asked.

Ariel chuckled. "Oh, Tethys. Come here, you." She said as she stopped swimming, before she pulled Tethys into a hug. Tethys smiled as he felt his older sister's embrace giving him the warmth and comfort he needed.

"I'll tell you something, Tethys; you have no idea how happy I was when daddy announced that you'll be our little brother." She said, still holding onto him closely.

* * *

 _*Flashback*_

" _ **The first night of you living with us, was the night I really got to see you for the first time."**_ _Present Ariel said as we see Young Ariel slowly sneaking inside Tethys's new room. It was dark, and it only had a small crib for the moment. Sooner or later, the family will either buy new toys for the boy or bring hand-me-downs from one of the older sisters._

 _Young Ariel looked into the crib, and saw the then-unnamed Tethys playing with the fins of his tail. She giggled, and approached him._

" _Hey there, little guy." She cooed softly. The baby turned to look at her, and upon seeing the familiar face, smiled with glee as he giggled. Young Ariel then swam to the top and looked down at him._

" _ **I'll never forget what I've said to you that night."**_ _Present Ariel said as Young Ariel reached her hand out, and baby Tethys reached out to grab one of her fingers. "This is so amazing, little one. You, being the only boy in the family…it makes you so unique." She said. Baby Tethys giggled some more._

" _I'm Ariel; youngest daughter of King Triton, who will be your daddy too. That's a wonderful privilege." She said, smile growing wider. Baby Tethys giggled again, wiggling his tiny tail, which made her laugh. She then sighed, and placed her hand on his left cheek._

" _Little one…whose name I don't have…from this moment on, I'm gonna keep you safe with me." she said. "Your old family may be gone…and some of my sisters are not too keen on keep you here. But they don't matter right now." She said._

 _Baby Tethys looked on in admiration as Young Ariel lifted him up and held him closely to her chest. Baby Tethys listened in to her heartbeat. "What matters…is that you will grow up to be a strong merman in the future…a nice and kind, strong merman. And_ I _," Young Ariel said as she held him._

 _*Flashback ends*_

* * *

"will be there to help you through and through." Ariel said as the memory fades away to the current time. Ariel placed a hand on Tethys's hand. "You matter a lot to me, Tethys. You're the first brother I ever had. As much as I love my sisters, it gets a little bit boring. You know, having to listen to drama all the time. All in all, it feels…dull." She said with a shrug.

Tethys looked at her, a bit bewildered. "Really?" he asked. Ariel nodded. "Flounder did help make things livelier. But…with you," she said, before swam behind him and picked him up, hugging him tightly. "YOU bring so much more life into my own. You are a bit lazy at times, and messy, especially when we visit the Manatee Farm…but guess what?" she asked. "What?" Tethys replied.

Ariel leaned into his ear with a smile. "You're MY little lazy, messy boy. And I wouldn't want you in any other way. THAT'S a fact." She whispered, before kissing him in the cheek.

Tethys blushed a bit, allowing her words to sink into his heart. With a trembling sigh, he leaned into her embrace. "I love you, Ariel." He said softly. Ariel smiled as she closed her eyes. "I love you too, Tethys. You are, have been, and always will be a part of MY world." She cooed softly as she rocked him side to side softly. Tethys just had to smile.

After a while of silence, Tethys decided to have his fun with Ariel. Using his tiny hands, he reached down, and tickled Ariel underneath her shoulder. Ariel laughed as she lets him go.

"Hey." She said with a smile. Tethys stuck his tongue out. "That was for being my loving sister." He said, referring to what Ariel said from earlier after he asked why did she 'hate' him. Ariel growled, and then grew a devilish smirk, arms standing to a threatening pose.

"Look out, Tethys. The tickle monster is coming for you!" she growled. Tethys squeaked as Ariel lunged for him, barely dodging her by an inch. Ariel then turned back to see him swimming away. "Catch me if you can, slowpoke!" he taunted.

Ariel just had to laugh "evilly" as she ran after him. "You'll pay for that!" she shouted as she swam after him, though a genuine smile threatens to break her character for a moment.

And so, for the rest of that morning, Ariel chased Tethys throughout the reef. The bond between these two will never break, even as time passes. If anything, the love for the two merpeople having fun will only grow stronger than the tidal waves crashing against a cliff…

* * *

 **AN: Hey there, superkoola here.**

 **I'm not entirely sure as to why I decided to write this. It's basically a one-shot of the Little Mermaid with Ariel having an adopted brother living with her. Honestly, it just feels like it's something I want to get the idea off my mind.**

 **Having written this, I'd like to write more about Ariel, Tethys, and their life in and around Atlantica. I love that world since I was a little guy, being introduced to the Little Mermaid universe with** _ **Return to the Sea**_ **.**

 **I hope you enjoy this, and stay tuned for more!**


End file.
